David Rowe has a fascinating blog on open-source telephony that features a surprising amount of technical detail. If you're interested in telephony, this is definitely worth checking out.

And of course I can't talk about blogs without mentioning TI's blogs. These blogs are just as corporate-flavored as you would expect, but they are worth checking out. I particularly enjoying reading the entries written by Gene Frantz, who always has interesting things to say about the future of DSP.